This invention relates to a braiding machine for the production of fiber reinforced plastics (FRP) and more particularly to a braiding machine in which a resin impregnation of the fibers is effected prior to a braiding of the resin impregnated fibers about a mandrel.
The increasingly wide spread use of FRP for industrial, recreational and aerospace applications has stimulated research into new methods for manufacturing FRP components. Braiding machines for braiding the fibers to effect the reinforcement offer several advantages when adapted to make FRP parts. Braiding equipment is generally much less expensive than winding or pultration equipment, braiding is inherently capable of forming tapered or irregular geometry parts and a braided structure provides a better balance of physical properties because of the innerweaving of the fibers functioning to provide the reinforcement to the plastic structure.
A major difficulty in adapting commercial braiding equipment to produce FRP components is the necessity to impregnate the fibers in a thorough and continuous manner without resin waste or contamination of the work area. Optimum strength is obtained only when the fibers are fully resin impregnated with no significant voids or air bubbles. Conversely, large pockets of resin (resin-rich) must be avoided.
In the past, impregnation has been accomplished by using pre-impregnated fibers or by wrapping partially cured (B-stage) resin film around the braid after each layer is completed. However, these partially cured resin products are expensive, have limited shelf life even when stored in a freezer and applying the partially cured resin film is cumbersome and slow.
It is therefore a primary object of the present invention to provide an improved braiding machine for continuously impregnating fibers during braiding or weaving and to thereby produce high quality, low cost composite parts.
It is a further object of the present invention to provide an improved braiding machine of this type in which resin waste and contamination is minimized, impregnation is complete for each filament, the resin content of the finished product is uniform and wherein a braiding may be achieved bidirectionally by momentarily halting the operation and tying the braid in place.